This invention relates to an annular stator core construction and particularly an annular stator core for a multiple pole exciter stator of the exciter for energizing an A.C. synchronous alternator.
The stator of an exciter for an A. C. alternator is formed with special mounting as an integrated assembly with the A. C. synchronous generator. The environmental and usage conditions require a solid rigid mounting of the stator. In the construction of the an integrated assembly, the exciter is preferably a small compact unit. The exciter generally should be such as to produce maximum power output, which requires maximum electrical and magnetic efficiency. Generally, the stators are formed as an annular member having internal coil supporting poles. The poles are formed with outer coil retaining heads, or tooth tips and the coils are wound in a more or less random manner directly on the poles. The laminated stator core is mounted within a supporting frame structure such as a conventional round frame or directly mounted to a supporting bracket.
U.S. Pat. No. 2,777,080 which issued Jan. 8, 1957 discloses a rectangular core structure having a pair of short poles to one side of the rectangular core and relatively long poles to the opposite major side of the rectangular core. Inner corner poles are located between the short and long side poles, each having a length essentially corresponding to that of the long side poles on the major axis of the rectangular core. The poles are similarly formed with well known integral coil retaining heads, requiring winding of the coil onto the poles in accordance with generally accepted present day commercial day practice.
U.S. Pat. No. 1,426,923 which issued Aug. 22, 1922 diagrammatically illustrates a somewhat similar construction with a plurality of equal length poles circumferentially distributed about an annular support. The poles have straight side and the structure for retaining the coils in place is not shown.
U.S. Pat. No. 2,907,904 which issued Oct. 6, 1959 discloses a circular core having a plurality of circumferentially distributed poles including relatively wide poles and narrow poles located between the wide poles. The poles are shortened slightly by chordal portions formed in the outer core portion adjacent the wide poles. The wide poles are formed with integral coil retaining heads for retaining of the wound coils while the relatively thin interpoles are shown with a constant cross section and special encircling retaining devices on each of the small poles to hold the coils. The adjacent poles have side groove portions to receive bridging magnetic members.
The prior art thus has provided a significant number of different types of pole construction for annular stator units with various means for locking of the coils onto the poles.
Although various systems have been provided, there is a need for a compact, high power exciter for optimum integration with an A.C. sychronous generator set and the like.